80th day of 2017.
I tested out a cheapo colored leads 2mm size, and as expected from the price range, it somewhat erased like Col-erase and it is hard to put graphite on top of it. So I better treat those as plain colour pencils?
It comes in 3 colors, RGB, red, green and blue. Although judging on the dark saturation of the lead colour, it would be more difficult to isolate it out via photoshop. Best color to use as construction lines beneath black lines are CMY, cyan, magenta and yellow.